September 2018       Volume 9, No. 4

Dear Friends,

I've been enjoying some weekend garden tours this summer, a nice chance to take some shady back roads and travel in a new direction for inspiration.  The July tour of historic homes and gardens in Hancock, New Hampshire was particularly rich in detail and abundant bloom.  A series of garden rooms in a remote setting was created by an off-the-grid couple in the 1980s who now garden full-time among choice trees, shrubs, perennials, vegetables, and annuals.  A hedge of phlox over 6' tall growing in a wet meadow near the town center had not one spot of mildew and was in full, glorious bloom!

Read on for more glories (and scourges) of late summer.
September Pests and Diseases - Lacebug, Fall Webworm, Magnolia Scale, Sooty Mold, Mildew and What to Do
This weather pattern of blazingly hot followed by wet and cool is perfect for many pests and diseases in the landscape.  During our pruning work, we've noticed the following:

Lacebug on pieris, boxwood, cotoneaster, azalea and small leaf rhododendron - You will see a tell-tale yellowing of broadleaf evergreen foliage from a distance sometimes.  As you draw nearer, you see that the leaves are covered with yellow pin pricks.  This is the sucking action of the lacebug, quite literally drawing the sap from the leaves.  Eggs are laid on the back side and look like small black dots.  
We can spray foliage with a Neem oil product to smother this pest and its eggs.    One caution is to avoid using this product when temperatures are above 80 degrees so it does not burn foliage.  A good follow-up plan is to test and amend soil this fall.  A soil with Phosphorus in balance nurtures shrubs that are less attractive to insect pests.

Fall Webworm emerges in July, making its web-like cocoon nest at the end of tree branches in the rose family (apple, crabapple, cherry) but also favors birch, hickory and lilac.  The easiest remedy is to reach up and remove the cocoon and its larvae from the site.  Sometimes this has to be pruned out.  Spraying with Insecticidal Soap also helps, provided we can reach the area with our spray equipment.  Only the nest itself needs to be sprayed .
Fall webworm in Cherry Tree

For more about this pest, see the excellent information provided by  Pennsylvania State University at

Magnolia Scale is again prevalent this season.  Look for white dots on the magnolia branches.  You may also see black soot-like mold on the leaves of the tree, on plants growing beneath it, or on nearby hardscapes.  This so-called sooty mold is a byproduct of the scale pest.  Unfortunately, sooty mold also attracts bees and wasps that collect its honeydew.  So it can be downright dangerous to stand or work near a magnolia tree at this time of year.
Magnolia Scale on branch

We use a multi-prong approach to these issues.  First of all, keep your magnolia pruned and open to allow good air circulation.  Scale will congregate where air does not flow well.  If your tree already shows extensive sooty mold, we will have to wait until the dormant season (November) to prune it due to the danger of stinging insects. 

Second, improve the soil around the plant this fall per soil test results. 

Third, the tree can be sprayed with a combination of a Neem oil product, horticultural oil, and a natural product derived from the chrysanthemum plant to stop the spread of the scale.  Our spray equipment can reach trees up to 20' high; above that please call an arborist.  Note that we will wait to spray when we see small white crawlers emerge next spring - this is the early development stage of the scale pest.  At their most vulnerable, the spray will then be effective on the crawler.

Our Plant Health Care Manager, Al Newman, already has this action on his scouting calendar for 2019 and will notify you about the timing of his spray route.  We will use our 200 gallon power sprayer for this work.

Mildew may have formed on phlox, peony, lilac and dogwood, among other plants.  This is not fatal to the plant, just temporarily disfiguring.  I use signs of mildew as a cue card.  It tells me that we need to amend the soil as a preventative and/or move the plant to a better position where air will circulate.  All such work is best done this fall.  Thinning the plant by dividing or removing selected stems outright is another good strategy to prevent mildew.  
Mildew of Phlox

If caught early, we can also spray the plant with an organic fungicide.  However, this product does not work well on leaves that are already predominately white.  At this stage, we recommend cutting the plant down early and disposing of the infected leaves in the trash.  For the dogwood tree, leaves may defoliate early, and if so, rake up promptly and dispose away from the site.

Success with Container Seeds
I've had a lot of fun this summer with container vegetables.  Since I ran out of space in the ground that receives more than 6 hours of sun many years ago, I constantly search out varieties that will thrive in my collection of pots.  I can rotate the containers into the sun as needed, another plus.  This spring I discovered that Renee's Garden has an extensive line of vegetable, herb and flower seeds bred to be just perfect for containers!  Another trusted supplier is Fruition Seeds from upstate New York.
Mini Basil 'Piccolino'

The mini basils have been particularly successful.  Here is 'Piccolino' with very tiny leaves.  I snip off the stalks with my sharp harvest scissors, then strip the leaves by hand.  No chopping needed!    Another great variety is 'Italian Cameo' with large leaves but a height less than 12."  We started 'Piccolino' from seed indoors under lights.  I scattered the seeds of 'Italian Cameo' directly in the pot sometime in June and soon was harvesting.

Basil 'Italian Cameo'

The dwarf nasturtium 'Elf' from Select Seeds has been charming both me and the hummingbirds.  I keep its pot on my deck railing near the breakfast table to watch the action.  The flowers are edible, too.

In spring I enjoyed Fruition's mesclun mix of lettuces and herbs called 'Salade de Provence' and used it cut-and-come-again style by snipping off the greens at the base.  The plants quickly resprouted for a second and then a third round.  Mesclun mix does best in cool weather.

Our excess kale and beet seedlings have been giving me multiple harvests of microgreens this way all summer.  Next up will be Renee's dwarf bush bean 'French Mascotte' and cucumber 'Bush Slicer.'  I'm pushing the envelope on these since I just remembered to put the seeds in the pots near the end of July.  But with the warm falls we've had in the past few years...and my solar greenhouse...I just might get my harvest after all!
Visit to deCordova Sculpture Park
You may enjoy a late summer visit to the deCordova Sculpture Park and Museum in Lincoln.  The grounds are cool and lovely, with well-maintained shade and ornamental trees, intriguing sculptures around every bend in the path.  If a shower blows up, duck indoors for exhibitions, eat at the cafe or visit the shop.  See for hours and further information.

PBOG will be renovating the entry garden by Sandy Pond Road this fall, implementing a design plan by our colleague Natalie deNormandie of Sego Design.  Natalie also designed the lovely perennial gardens bordering the outdoor cafe which were full of pollinators on my recent visit.
Plant Pick:  Oxydendrun arboreum (Sourwood Tree)
While at deCordova, you won't be able to miss the mature Sourwood Tree, Oxydendrum arboreum, not far from the front entry drive at the edge of the woods.  The tree comes into bloom in late August, and this specimen is covered in white dangling blossoms.  As fall progresses, the foliage turns brilliant shades of red, orange and copper and the blossoms remain intact for a tremdendous show.
Oxydendrum arboreum Sourwood Tree

A native of the southern Appalachian mountain range, the Sourwood does well in our region if given a protected spot in the woodland understory or in a courtyard situation.  It grows very slowly, although we have been seeing some success by installing small container plants in your gardens.  I'm happy to report that the plants are now gaining some girth!
Concord Food, Farm and Garden Fair, September 8 and 9
Mark your calendar for the annual Concord Food, Farm and Garden Fair the second weekend of September!  This new tradition features vegetables, fruit, and flowers grown in by Concord's farmers, as well as tours of kitchen gardens and farms.  The Saturday morning Farm Market on Main Street is not to be missed, so bring the kids to create a zucchini car to race!  Local restaurants also feature local food specialities.

This is a free event sponsored by the Town of Concord Agriculture Committee, Garden Club of Concord and the Concord Carlisle Food Collaborative.  For details, see the full schedule of events at
Planning for fall:  bulb order, transplanting and dividing work, soil amending, planting!
Now is the time to look ahead to fall gardening.  We have opened the bulb catalogues to design and plan spring bulb displays.  Please let Priscilla know by September 10th if you would like to order spring bulbs.  We don't want your favorite varieties to be sold out!  Our crews will be planting bulbs between Columbus Day and Veteran's Day, as bulbs need time to root before the ground freezes.

Fall planting started in mid August, as we might as well go along with the weather pattern of frequent rain, cloudy days and (somewhat) cooler temperatures.  I'm excited to report that the ground is full of moisture and ready to receive new plants.  Planting season will continue through the end of October.   We have more clients than ever before already lined up for fall plantings, but there is certainly space for a few more.  Remember this is also the ideal time to transplant a shrub, divide and transplant perennials, and rearrange the garden in general.

Soil tests will be taken during the month of September so we can plan ahead for soil amending in October and November.  We utilize nutrient density methodology and aim to balance nutrients and supply the minerals that may be lacking each fall.  This is the best time for the roots of woody plants and perennials to take up such nutrition, as roots are actively growing and setting buds for next year during the cooler temperatures of fall.  Once your vegetable garden is cleaned up for the season, we can test and amend soil there as well, giving you a leg up on 2019 spring planting!
Priscilla's To-Do List for September
  • Keep up with weeding
    Grape Hyacinth
  • Deadhead weekly to promote more bloom
  • Top off mulch if it has degraded in the frequent rain and intense heat
  • Scout for slugs if you see holes in leaves and apply Sluggo (a product containing Iron phosphate that is toxic to slugs)
  • Continue to keep rabbits and deer at bay with garlic clips (good for 8 months)
  • Harvest vegetables regularly to keep the yield high
  • Remove and clean up any spent vegetable crops promptly and replant with fall seedlings of lettuce, kale, escarole or other greens
  • Finish summer pruning of spring blooming trees and shrubs
  • Plan fall planting and spring blooming bulb order
  • Plan fall dividing and transplanting projects
  • Bearded iris crowded together can be divided now
  • Scout for scale and lacebug in the landscape

I look forward to seeing you soon in the garden and to collaborating on fall gardening tasks!


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